It is known to press a commutator ring provided with intersegmental grooves into a hollow cone and thereby reduce its size. This can cause the cross pieces in the longitudinal grooves between the individual commutator segments in the hollow core's inner wall to crumple outward so that they protrude on the rolling surface of the commutator segments. The crosspieces are removed from the segments in a later manufacturing step. Anchoring means are formed on the inner sides of the commutator segments and project radially into the segmental grooves. This known method has the disadvantage that the commutator ring is formed by axial movement of parts of the apparatus. Cold-forming using this process results in segments in the region of the ends which have a smaller cross section than those in the middle of the commutator ring. In the region of the ends of the commutator ring, there is less material on the inner side of the commutator segments for formation of anchoring means. The commutator segments can therefore not be securely fastened into the insulating hub, so that in fast-running electrical machines the commutator segments are pulled by centrifugal force out of their anchorage in the insulating hub.